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Lime plaster
Non-hydraulic lime can only set through carbonation (re-absorption of CO2). It is often sold in builder's merchants as 'bagged' or hydrated lime or is available as lime putty (or as quicklime to be made into lime putty), lime putty generally being considered more suitable for pure lime application. Non-hydraulic lime is the most commonly used and known lime, also called (high) calcium lime or air lime, as it sets only by reaction with in the air and will not set until dry. This causes limitations in construction use as the lime can remain soft for months or years. Hydraulic and hydrated limes must not be confused. Hydrated lime is merely a form that lime can be supplied in (as opposed to quicklime or lime putty) while 'hydraulic' refers to a characteristic of the lime. Safety issues Lime is an extremely caustic material when wet, with a pH of 12. (Lime becomes pH neutral when carbonated). As such, the use of protective goggles, gloves, and clothing are necessary when working with lime. Clean water should also be kept readily accessible for first aid purposes when working with lime in case of accidental eye or skin exposure. First aid for cases of skin exposure to lime involves neutralization with very mild acid such as vinegar or lemon juice. First aid for cases of accidental eye exposure consists of repeatedly flushing the eye for several minutes with fresh water. Medical attention should be sought in such cases.Hagsten, Ellen. General Guidelines for Working with Lime Mortar and Limewash, Traditional & Sustainable Building, March 2007 Uses in building Some of the earliest known examples of lime use for building purposes are in early Egyptian buildings (primarily monuments). Some of these examples in the chambers of the pyramids, which date back to around 2000 B.C., are still hard and intact. Archaeological digs carried out on the island of Malta have shown that in places like Tarxien and Hagar, lime stucco was also used as a binder to hold stone together as well as for decoration at sites dating back as far as 3000-2500 B.C. At el-Amarna, a large pavement on brick was discovered that dates back to 1400 B.C. It was apparently the floor of part of the harem of King Amenhotep IV.Cowper, Ad. Lime and Lime Mortars, first published for the Building Research Station by HM Stationery Office, London, 1927 Ancient Chinese used Suk-wui (the Chinese word for slaked lime) in the construction of The Great Wall of China. The Aztec Empire and other Mesoamerican civilizations used lime plaster to pave streets in their cities.ISBN 978-0-500-28714-9 It was also used to coat the walls and floors of buildings. See also References Further reading Cedar Rose Guelberth and Dan Chiras, The Natural Plaster Book: ''earth, lime and gypsum plasters for natural homes' J.N. Tubb, ''Canaanites, London, The British Museum Press, 1998 Stafford Holmes, Michael Wingate, Building With Lime: A Practical Introduction, Intermediate Technology Publications Ltd, External links * [http://www.howardhallfarm.com/limemortar.html General Guidelines for Working with Lime Mortar and Limewash, Ellen Hagsten,Traditional & Sustainable Building, March 2007] * British Museum: Lime Plaster Statues * Yuval Goren, Paul Goldberg, Peter W. Stahl and Udo H. Brinker Journal of Field Archaeology, Vol. 18, No. 1 (Spring, 1991), pp. 131–140, Published by: Boston University Category:Building materials